EFFECTS OF COCAINE SELF-ADMINISTRATION ON ETHANOL, FOOD AND WATER-INTAKE IN THE RAT

Because cocaine and ethanol are frequently abused in combination, the present study was performed to assess the behavioral consequences of c oncurrent access to both of these drugs. Rats trained to respond for f ood under a fixed-ratio 40 (FR 40) schedule of reinforcement during fo ur, 30-min periods each day (every 6 h) were given free access to a 5% (w/v) ethanol solution and to water. Once a stable baseline of food, ethanol and water intake was established, intravenous cocaine was made available under a fixed-ratio 1 (FR1) schedule. After cocaine self-ad ministration had been established for 10 days, the ethanol was removed from the chambers for 3 days. After the ethanol was returned to the c hambers, saline was substituted for cocaine for 3 days. Following sali ne substitution, animals were given increased cocaine availability. Be fore cocaine was made available, rats consumed primarily the ethanol s olution, averaging 31.7 ml of the 5% solution (4.2 g/kg ethanol), 10.2 ml of water and 148 food pellets/day. When cocaine (0.2 mg/kg per inj ection, i.v.) was made available, rats self-administered an average of 40 - 85 injections per day. Self-administration of cocaine resulted i n small decreases in ethanol and food intake, as well as some changes in the pattern of ethanol intake. However, removing the ethanol from t he chambers had no effect upon food and cocaine intake. Substitution o f saline for the cocaine altered the pattern, but not the amount of et hanol intake. There was a trend toward increased ethanol intake during the study, which may have been related to repeated cycles of cocaine availability.